Alkylated poly-n-vinyl-lactam stabilized silver halide emulsions



United States Patent 01 fice 3,505,067 Patented Apr. 7, 1970 3,505,067 ALKYLATED POLY-'N-VINYL-LACTAM STABI- LIZED SILVER HALIDE EMULSIONS Fritz Dersch, Binghamton, and Richard P. Armentrout, Marathon, N.Y., assignors to GAF Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed Mar. 16, 1967, Ser. No. 623,551 Int. Cl. G03c 5/30, 1/34, 1/72 U.S. C]. 96-66 Claims ABSTRACT OF THE DISCLOSURE Stabilizers for light-sensitive silver halide emulsions containing as a stabilizer agent a compound comprising an alkylated polymer of a heterocyclic N-vinyl monomer of the lactarrr series in which the alkyl radical of said polymer contains from 2 to 2000 carbon atoms.

The present invention relates in general to the provision of novel additives for improving the anti-fogging properties, sensitivity, contrast, covering power, etc. of photographic silver halide emulsions and in particular to the employment of alkylated derivatives of N-vinyl lactam polymers for such purposes.

As is well known, the sensitivity of light-sensitive silver halide emulsions can be increased in a number of ways as for example by the incorporation therein of one or more chemical or optical sensitizing agents which function to augment and/or extend the emulsion sensitivity to light of longer wavelengths.

In general, it is postulated that chemical sensitization results from the formation of small amounts of silver sulfide and/or silver on the surface of the silver halide crystal. As examples of compounds found to function as chemical sensitizing agents there may be mentioned sodium sulfite, sodium thiosulfate and the like. Procedures designed to effect chemical sensitization of photographic silver halide emulsions may be implemented for example by carrying out the digestion step in the presence of naturally active gelatin, i.e., active photographically, or alternatively, in the presence of auxiliary sulfur compounds, such as those described in U.S. Patents 1,574,944, 1,623,- 499 and 2,410,689. Other procedures of a similar nature involve for example the treatment of the emulsion medium with salts of the noble metals such as ruthenium, rhodium, palladium, iridium and platinum. Representative compounds of this type include, for example, ammonium chloropalladate, potassium chloroplatinate and sodium chloropalladite the use of such compounds for sensitizing purposes being described in U.S. Patents 2,448,060, 2,566,- 245 and 2,566,263.

The emulsion may also be chemically sensitized with gold salts such as those described in U.S. Patent 2,399,083 or stabilized with gold salts such as those described in U.S. Patents 2,597,856 and 2,597,915. Suitable compounds of this type include, for example, potassium chloroaurite, potassium aurothiocyanate, ammonium aurothiosulfate, potassium chloraurate, and auric trichloride.

Chemical sensitization may also be effected with the use of reducing agents such as stannous salts (U.S. 2,487,- 850), polyamines such as diethylene triamine (US. 2,518,- 698); spermine (U.S. 2,521,925); bis (,8 aminoethyl)- sulfide and its water soluble salts (U.S. 2,521,926); formamidine sulfinic acid or derivatives thereof (U.S. 2,983,- 609 and U.S. 2,983,610); imino-amino-methane sulfinic acid (Belg. 547,323); hydrazine and hydroxylamine (French 1,146,955); formaldehyde sulfoxalate (U.S.

2,604,297); sodium hydrosulfite (U.S. 1,623,499); organic phosphites (German application 1,187,925); ascorbic acid (U.S. 2,448,060); etc. Particularly beneficial results as regards efiiciency of chemical sensitization are purportedly obtained with such compounds as the polyoxyalkylene ethers and numerous derivatives thereof such as the products obtained by reacting alkylene oxide with reactive hyd-rogen-containing organic compounds, e.g., acids, alcohols, amines, etc. The use of the foregoing and related compounds for such purposes is well established in the prior art being extensively described in the patent and trade literature. Other compounds proposed for use in a similar relationship include the quaternary ammonium, phosphonium and ternary sulfonium salts as well as combinations or mixtures of one or more of the foregoing compounds with alkylene oxide polymers.

Other problems frequently encountered in the emulsionmaking as well as the emulsion-processing industries relate to the production of relatively high speed emulsions which enable the attainment of image reproductions characterized by satisfactory contrast as well as covering power of the developed silver. As is well known, the term covering power is a measure of the silver concentration in the developed image and is derived arithmetically by dividing the optical density at maximum density by the grams of silver per square decimeter in the developed image layer.

Representative of the materials heretofore promulgated for use as emulsion addenda to thereby obtain the requisite contrast, silver covering power, etc., include, for example, the poly-N-vinyl lactams, the water-soluble polyglucose dextrans, water-soluble B-hydroxyalkyl ethers of polyvinyl alcohol, water-soluble hydrolyzed glycogen, water-soluble mannan polysaccharide, the water-soluble polyglucose laminaria, hydroxy-ethyl cellulose, carboxy-methylated proteins and the like.

While the foregoing and related compounds have been found in the vast majority of instances to provide some measure of improvement their use is invariably accompanied by other significant drawbacks which tend to detract considerably from their commercial desirability. For example, many of the foregoing compounds must of necessity be employed in inordinately large proportions resulting in a depression of the melting point of the emulsion layer which, in turn, leads to such undesirable defects as reticulation, the latter becoming particularly manifest in those instances wherein the emulsion is subjected to high temperature, high-speed processing. Moreover, such compound can present serious problems of fog and especially when the emulsion containing same is stored for any significant period of time under even moderately severe conditions of temperature and/ or humidity. A further deterrent to the use of the compounds thus far known resides in their pronounced tendency to cause turbidity either in the wet or dry state of the emulsion layer.

In an effort to overcome or otherwise alleviate the foregoing and related disadvantages, considerable industrial research and development has centered around the provision of compounds which, when incorporated into light-sensitive silver halide emulsion layer, impart thereto acceptable photographic speed, contrast and covering power while reducing substantially any tendency of the emulsion to fog. However, despite the extensive industrial effort in this regard, the compounds thus far suggested have been found, characteristically, to provide a satisfactory measure of improvement only at the expense of other essential emulsion properties.

Thus, a primary object of the present invention resides in the provision of improved light-sensitive silver halide emulsions as well as photographic elements fabricated therewith wherein the above and related disadvantages are eliminated or at 'least mitigated to a substantial extent.

A further object of the present invention resides in the provision of improved light-sensitive silver halide emulsions characterized by outstanding improvement in photographic speed, contrast end covering power of the silver image developed therein.

A still further object of the present invention resides in the provision of improved light-sensitive silver halide emulsion substantially devoid of any tendency to fog and further characterized by outstanding stability even under severe conditions of temperature and/or humidity.

Other objects and advantages of the present invention will become apparent hereinafter as the description thereof proceeds.

The attainment of the foregoing and related objects is made possible in accordance with the present invention which, in its broader aspects, provides bringing into operative association with a light-sensitive photographic emulsion, an alkylated polymer of a heterocyclic N-vinyl monomer of the lactam series in which the alkyl radical of said polymer contains from 2 to 2000 carbon atoms.

The alkylated, N-vinyl lactam polymers contemplated for use in practicing the present invention are those prepared by alkylation of a homoplymer or copolymer of a heterocyclic N-vinyl monomer, preferably a N-vinyl lactam monomer and most preferably N-vinyl pyrrolidone monomer with an alpha-olefin containing from 2 carbon atoms to 2000 carbon atoms preferably in the range of from 2 to 200 carbon atoms, and most preferably in the range of from 8 to 42 carbon atoms, said alkylation process being more fully described in GAP Corporations US. Patent 3,417,054. As described therein polymers of heterocyclic N-vinyl monomers are readily alkylated by treating one mole of a homopolymer or copolymer of a heterocyclic N-vinyl monomer with 0.05 to 10 moles of an alpha-olefin of at least 2 carbon atoms in solution of an organic solvent common to the polymer and al ha olefin in the presence of 0.025 to 0.30 mole of an organic peroxide catalyst per mole of alpha-olefin, at a temperature ranging from 100 to 200 C. for a period of time ranging from 3 to 60 hours. The resulting solution of the alkylated polymer may be employed as such or, if desired, the organic solvent may be removed by vacuum distillation.

As noted above, an organic solvent is employed in the alkylation reaction which is common to the polymer (homo or copolymer) and alpha-olefin(s). As solvents,

various alcohols, such as methanol, ethanol, propanol, iso propanol, butanol, sec-butanol, amyl alcohol, hexanol, 2- ethyl-l-hexanol, ethylene glycol, 1,2-butanediol, 4-butanediol, etc., may be employed. Other inert solvents such as diethylene glycol, ethylene glycol monomethyl ether and the like may also be employed. It is to be noted that the nature or character of the organic solvent is immaterial so long as it forms a solution with the polymer and alkylating alpha-olefin(s) and is not susceptible to alkylation.

As peroxide catalyst (initiator) for the alkylation reaction, any one of the known tertiary-alkyl organic peroxides and hydroperoxides such as, for example, di-tbutyl peroxide, t-butyl perbenzoate, di-t-butyl peroxide, t-butyl perbenzoate, di-t-butyl perphthalate, t-butyl-pentamethylethyl peroxide, t-butyl-triphenylmethyl peroxide, dit-amyl peroxide, bis-(triethylmethyl) peroxide, bis(triphenylmethyl) peroxide, 2,5-dimethyl-hexyl-2,S-dihydroperoxide, 2,5-dimethyl-2,5-di(t-butyl peroxy) hexane, 2,5-

dimethylhexyl-2,5-di(peroxy benzoate), t-butyl hydropercyclic N-vinyl monomers and an alpha-olefin containing from 2 carbon atoms to 2000 carbon atoms, said simultaneous polymerization and alkylation process being more fully described in GAF Corporations US. Patent 3,423,- 367. As described therein, alkylated terpolymers are readily obtained by heating one mole of a mixture of monomers containing from 5 to 99 mole percent of a heterocyclic N-vinyl monomer having a carbonyl function adjacent to the nitrogen in its heterocyclic moiety and from 1 to 95 mole percent of a polymerizable monoethylenically unsaturated monomer with 0.05 to 10 moles of an alphaolefin or halo-alpha-olefin of at least 2 carbon atoms in solution of an inert organic solvent common to the mixture of monomers and alpha-olefin or halo-alpha-olefin in the presence of 0.025 to 0.30 mole of an organic peroxide catalyst per mole of alpha-olefin or halo-alpha-olefin at a temperature ranging from C. to 200 C. for a period of time of from 3 to 60 hours.

The same alpha-olefin or halo-alpha-olefin which forms the terpolymer, alkylates one or more active sites of the heterocyclic N-vinyl monomer moieties as well as one or more active sites in the polymerizable monoethylenically unsaturated comonomer in the terpolymer. In other Words, the alpha-olefin or halo-alpha-olefin terpolymerizes with the heterocyclic N-vinyl monomer and the monoethylenically unsaturated monomer. While the three (3) component mixture is being terpolymerized, the same alpha-olefin or halo-alpha-olefin also alkylates one or more of the active sites of the heterocyclic N-vinyl monomer moiety as well as the other comonomer in the terpolymer by an alkyl or haloalkyl group of the number of carbon atoms contained in the alpha-olefin or halo-alpha-olefin employed in the reaction.

The solution of the alkylated terpolymer obtained as above may be employed as such, or, if desired, the inert organic solvent may be removed by vacuum distillation, or other solvent evaporation techniques.

An organic solvent is employed which is common to the alpha-olefin, halo-alpha-olefin, the heterocyclic N- vinyl monomer and the polymerizable monoethylenically unsaturated monomer. As solvents, various alcohols, such as methanol, ethanol, propanol, isopropanol, butanol, secbutanol, amyl alcohol, hexanol, 2-ethyl-1-hexanol, ethylene glycol, 1,2-butanediol, 4-butanediol, etc., may be employed. Other solvents such as diethylene glycol, ethylene glycol monomethyl ether and the like may also be employed. It is to be noted that the nature or character of the organic solvent is immaterial so long as it forms a solution with the heterocyclic N-vinyl monomer, alphaolefin(s), halo-alpha-olefint's), and the polymerizable monoethylenically unsaturated monomer, and is relatively inert toward alkylation.

The amount of inert organic solvent employed is not critical. Any amount which will yield a solution of the mixture of the two monomers and alpha-olefin or haloalpha-olefin will sufiice. However, for purposes of expediency, We found that for every part by Weight of said mixture, from one to ten parts of organic solvent, either by volume or by weight, are suflicient to yield a workable solution.

As peroxide catalysts (initiator) for the polymerization and alkylation reaction, any one of the known tertiaryalkyl organic peroxides and hydroperoxides such as, for example, those described hereinabove.

As examples of N-vinyl lactam monomers which contain a carbonyl function adjacent to the nitrogen in the heterocyclic moiety, Whose alkylated polymeric derivatives produced as described in said US. Patents 3,417,054 and 3,423,367, may be employed in practicing the present invention may be mentioned N-vinyl succinimide, N-vinyl diglycolylimide, N vinyl glutarimide, N-vinyl-3-morpholinone, N-vinyl-S-methyl 3 morpholinone, N-vinyl- 5-ethyl-3-morpholinone, N-vinyl oxazolidone, etc., and N- vinyl ring oxygenated lactams as disclosed in United States Patent 3,231,548, and especially the N-vinyl 5-, 6- and H2O) OH:

wherein R and R are selected from the group consisting of hydrogen, methyl and ethyl, n is an integer of from 1 to 3, and m represents the average molecular weight as determined by relative viscosity measurement which are designated as K values.

The viscosity coefiicient, K, which is fully described in Modern Plastics, Vol. 23, No. 3, pages 157-61, 212, 214, and 216 (1945) is calculated as follows:

log 1; rel. 75 K,

and K=1000 K Where c is the concentration in grams per 100 ml. of polymer in solution and the 1 rel. is the viscosity of the solution compared to solvent.

There may also be used the alkylated polymers of comparable monomers of N-vinyl 5-, 6- and 7-membered thiolactams, N-acryloylpyrrolidone, -piperidone and -caprolactam; N acryloyl-5-methyl-pyrrolidone, N acryloyl- G-methyI-piperidone and N-acryloyl-7-methyl caprolactam and their corresponding 5-, 6- and 7-ethyl derivatives; N- acryloxy methyl pyrrolidone, -piperidone and -capro lactam; N-methacryloxy-ethyl-pyrrolidone, -piperidone and -caprolactam; N-methacryloxy-methyl-S-methyl pyrrolidone, -6-methyl-piperidone and -7-methy1-caprolactam; N-methacrylarnidomethyl-, N-methacrylamidoethyl-, N- methacrylamidopropyland N (n phenylacrylamidopropyl)-pyrrolidones, -piperidones and caprolactams.

The homopolymers of the N-vinyl lactams characterized by the foregoing formula (whose alkylated derivatives obtained, for example, as described in said US. Patent 3,417,054 are suitable for use in practicing the present invention) are readily obtained by homopolymerizing N-vinyl pyrrolidone; N-vinyl-S-methyl pyrrolidone; N- vinyl-5-ethy1 pyrrolidone; N-vinyl-5,5-dimethyl pyrrolidone; N-vinyl-5,5-diethyl pyrrolidone and N-vinyl-S-methyl-5-ethyl pyrrolidone; N-vinyl piperidone; N-vinyl-6- methyl piperidone; N-vinyl-fi-ethyl piperidone; N-vinyl- 6,6-dimethyl piperidone; N-vinyl-6,6-diethyl piperidone and N-vinyl-6-methyl-6-ethyl piperidone; N-vinyl-caprolactam, N-vinyl-7-methy1 caprolactam; N-vinyl-7,7-dimethyl caprolactam; N-vinyl-7-ethyl caprolactam; N- vinyl-7,7diethyl caprolactam and N-vinyl-7-methyl-7- ethyl caprolactam.

For the purpose of the present invention we employ alkylated derivatives of homopolymers of heterocyclic N- vinyl monomers having a K value ranging from about 10 to 140, preferably from about 30 to 100. These homopolymers are readily obtained by conventional homopolymerization procedures of the foregoing heterocyclic N-vinyl monomers described in United States Patents 2,265,450; 2,317,804; 2,335,454 and many others too numerous to mention in which working examples are given.

All of the homopolymers of N-vinyl lactams characterized by the foregoing general formula are soluble in water, alcohols, and certain classes of organic solvents, but insoluble in the aliphatic and aromatic hydrocarbons of the type hereinbefore mentioned.

Copolymers obtained by copolymerizing 5 to 99 mole percent of the foregoing heterocyclic N-vinyl monomers with 1 to 95 mole percent of a monoethylenically unsaturated polymerizable monomer and having a K value from about 10 to 140 are readily alkylated in accordance with the present invention to yield products having solubility characteristics dictated by the end use.

The various monoethylenically unsatmated polymerizable monomers, which are copolymerized with any one of the aforementioned heterocyclic N-vinyl monomers in the conventional manner and which will yield copolymers that are readily alkylated in accordance with said US Patent 3,417,054, to produce alkylated copolymers suitable for use in practicing the present invention, include vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl lactate, vinyl caproate, vinyl caprylate, vinyl oleate, and vinyl stearate; acrylonitrile; vinyl ketones; vinyl cyclohexane; styrene; 2-vinyl pyridine, 4- vinyl pyridine; acrylic acid; acrylate ester monomers of the formula:

CH =CHCOOR wherein R represents either a straight or branched alkyl of from 1 to 18 carbon atoms or an alkoxylalkyl in which the total number of carbon atoms in the alkyl groups range from 3 to 6.

As examples of such acrylate esters the following are illustrative: methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl, Z-methyl-l-butyl, 3-methyl-1-butyl, 2-ethyll-butyl, amyl, 3-pentyl, 2-methyl-1-pentyl, 4--methyl-2- :pentyl, hexyl, Z-ethyl-hexyl, heptyl, 2-heptyl, octyl, 2- octyl, nonyl, 5-ethyl-2-nonyl, decyl, 2-methyl-7-ethyl-4- undecyl, dodecyl, tetradecyl, hexadecyl, octadecyl, 2-methoxyethyl, 2-ethoxyethyl and 2-butoxyethyl acrylates; methacrylic monomers such as methacrylic acid, methyl methacrylate, cyclohexyl methacrylate, isobutyl methacrylate, isoamyl methacrylate, B-methoxy ethyl methacrylate and oc-(O-ChlOlOPhGIlYl) ethyl methacrylate, ,B-phenoxyethyl methacrylate, a-phenyl ethyl methacrylate, phenyl methacrylate, o-cresyl methacrylate, p-cyclohexylphenyl methacrylate, 2-nitro-2-methyl -propyl methacrylate, diethylamino-ethylmethacrylate, ethylidene acetate methacrylate and glycidyl methacrylate, including esters of halo acrylic acids, such as methyl-2-chloro-acrylate, ethyl-achloro-acrylate, phenyl-u-chloro-acrylate, a-ethylacrylic acid; methacrylonitrile; N-alkyl and N-aryl substituted acrylamides such as N-methyl acrylamide, N-ethyl, acrylamide, N-propyl acrylamide, N-n-butyl acrylamide, N-ndodecyl acrylamide, N-n-octadecyl acrylamide, N,N-dimethyl acrylamide, N,N-diethyl acrylamide, N-N-di-nbutyl acrylamide, N,N-di-isobutyl acrylamide, N-cyclohexyl acrylamide, N,N- dicyclohexyl acrylamide, N-phenyl acrylamide, N-p-nitro-phenyl acrylamide, N-a-naphthyl acrylamide, N-fl-naphthyl acrylamide, N-methyl N-phenyl acrylamide, N,N-diphenyl acrylamide, N-benzyl acrylamide, N,N-di-benzyl acrylamide; and grafted monomers of the type disclosed in United States Patents 3,029,219; 3,035,009; 3,036,033 and the like.

A mixture consisting of from 5 to 99 mole percent of any one of the foregoing heterocyclic N-vinyl monomers and from 1 to mole percent of a different heterocyclic N-vinyl monomer, such as, for example, N-vinyl lactam with either N-vinyl succinimide, N-vinyl-3-morpholinone, and the like, may also be copolymerized and the resulting copolymer alkylated for use in the present invention.

It is to be noted that any copolymer containing not less than 5 mole percent of the heterocyclic N-vinyl monomer and which is soluble in the organic solvent is readily alkylated in accordance with the present invention. From numerous experiments connected with the present invention, it has been found that the configuration of the foregoing monoethylenically unsaturated monomers, and numerous others, is immaterial since they all copolymerize in the aforementioned proportions With the heterocyclic N-vinyl monomers and yield copolymers which are soluble in the organic solvent or mixture thereof and which are readily alkylated.

With regard to the u-OlCl'lIlS employed for producing the alkylated polymers used in practicing this invention, it is to be noted at the outset that any a-olefins having a molecular weight from about 28 to as high as about 28,000, may be employed as the alkylating agent for the alkylated polymers of the various heterocyclic N-vinyl monomers. As examples of such lZ-O1finS, the following are illustrative: ethylene, propylene, l-butene, l-pentene, Z-ethyl-l-butene, Z-methyl-l-pentene, 1-hexene, S-methyll-hexene, Z-methyl-l-pentene, 3-e'thyl-l-pentene, l-heptene, l-octene, l-nonene, Z-ethyl-l-hexene, l-decene, 1- dodecene, l-tetradecene, l-hexadecene, l-heptadecene, 1- octadecene, l-nonadecene, l-eicosene, l-docosene, l-tetracosene, l-pentacosene and polybutenes of molescular- Weight of 400 to 2500 may be employed.

While linear oc-olefins are preferred because of their commercial availability, numerous isomers of iii-olefins ranging from l-pentene to l-pentacosene as Well as polybutenes may also be employed in the alkylation reaction. The only requirement in such case is that the isomer contain ethylenic unsaturation in the on position thereof.

Instead of employing any one of the foregoing individual tit-olefins, a mixture of commercially available linear lit-olefins produced by cracking petroleum wax or by polymerizing lower olefins may also be used as the alkylating agent. Alpha-olefins in the carbon range of from 6- 7; 7- 9; ir- 11; ir- 15; and C15"C20 are commercially available and may be used. A mixture of a'olefins containing from 65 to 75 percent of OL-OlCfiIlS of from C to C carbon atoms having an average molecular weight of 366 is also commercially available and such mixture is employed in the alkylation reaction.

In accordance with the discovery forming the basis of the present invention, it has been ascertained that silver halide emulsions of reduced fog, increased speed, contrast, and covering power of the developed silver can be obtained by including the alkylated polymer in the light-sensitive silver halide layer, an undercoating, an intermediate coating, an overcoating and/or a surface coating. The concentrations employed are not particularly critical so long as sufiicient amounts be present to impart to the emulsion the desired characteristics. Thus, the alkylated polymer may be advantageously employed in concentrations varying over a relatively wide range and preferably from about 1 to about 40 grams per mole of silver halide.

Within the aforesaid range, the amount selected will depend upon a variety of factors including for example the type of emulsion used. With emulsions of the high speed ammonia type, it is found that the use of 1 to 10 grams of the above described polymer material per mole of silver halide is particularly beneficial. Furthermore, in those embodiments wherein the alkylated polymer is incorporated into a non-sensitized auxiliary layer, e.g., antiabrasion layer, undercoating, etc., it is usually preferred that such material be utilized in the higher concentration range. In this manner, it is assured that a sufficient amount of the polymer material will be brought into operative association with the sensitized emulsion layer to thereby realize the improvements contemplated herein. Without intending to be bound by any theory, it has been postulated that the alkylated lactam polymer diffuses or otherwise migrates to the sensitized emulsion layer thus bringing about the desired intimacy of contact.

When added to the emulsion layer, the addition may be made during the actual preparation of the emulsion, either before or after the emulsion washing step and shortly before coating.

In any event, the polymeric materials contemplated for use in accordance with the present invention are available commercially from the GAP Corporation under the trade designation Ganex in a variety of grades throughout the molecular weight range hereinbefore specified. Particularly beneficial results are noted to obtain as regards fog suppression, enhancement of emulsion sensitometric properties, silver covering power, storage stability and the like with the use of the aforedescribed lactam polymer derivatives wherein the a-olefin component contains from about 12 to about 20 carbon atoms as typified by the commercial product Ganex V-516.

Perhaps the salient advantage presented by the use of the aforedescribed lactam polymer material relates to the fact that the speed of the photographic emulsion is in no way deleteriously affected notwithstanding the use of such material in relatively large amounts. Such compounds are of exceptional value as anti-fogging agents, and since little in the way of limitation is imposed as regards the concentrations employed significant increases in the photographic speed and contrast of the emulsion as well as the covering power of the developed image are readily obtained despite the use of proportions which would ordinarily, i.e., with the compounds heretofore provided in the art, result in severe fogging. In addition, it is found that the desired emulsion characteristics are obtained even under conditions of high temperature processing such as those required with the use of modern processing machines. The rather limited properties characterizing the stabilizer compounds thus far provided in the photographic art has necessarily imposed severe limitations upon the adaptability of photographic elements containing same to high speed machine processing.

Accordingly, it is of paramount commercial significance that photographic elements prepared with the polyrneric materials of the present invention are eminently suitable for such high speed machine processing in the virtual absence of fog, loss of speed, etc.

The following examples are given for purposes of illustration only and are not to be considered as necessarily constituting a limitation on the present invention.

EXAMPLE I A high speed, sulfur and gold sensitized silver halide emulsion in gelatin containing 4% silver iodide and silver bromide is prepared in a conventional manner and brought up to maximum light sensitivity. It is then readied for coating on film base, that is, melted at 40 C., necessary coating finals are added, such as sensitizing dyes, stabilizers and hardeners. A 10% solution of Ganex V-S 16 in isopropanol is prepared and a portion of this solution added to a test sample of the above-described emulsion containing about 0.6 mole of silver halide. A sample of the same emulsion, but not containing the compound of our invention, serves as a control. The so-prepared emulsion samples are coated onto a suitable cellulose ester base of the type conventionally employed in the art and dried. Samples of each of the film coatings thus prepared are thereupon exposed in a Type 13 sensitometer and developed in a developer of the following composition each of such operations being carried out in. identical fashion.

The following table summarizes the speed and fog measurements taken.

TABLE I Quantity of Ganex V-516 used per 0.6 mole of silver halide, grams Control 0 Test 2 Relative Fog speed 6' dev.

EXAMPLE II A high speed, sulfur and gold sensitized silver halide emulsion in gelatin containing 2% silver iodide and 98% silver bromide is prepared in conventional manner and brought up to maximum light sensitivity. It is then readied for coating as described in Example I. Coated film samples are likewise prepared in the manner described in Example 1. Both the test and control samples are then developed in the Eastman Kodak M4 X-Omat processing system. The results obtained are tabulated as follows:

TABLE 11 Quantity of Ganex V516 Relative used, grams speed Fog Control 100 0. 36 Test 1 100 0.33

A high speed, sulfur and gold sensitized silver halide emulsion containing 2% silver iodide and 98% silver bromide is prepared. Samples containing about 0.4 mole of silver halide are taken and experiments conducted as follows:

(a) Coated as control and provided with a 4 surface coating prepared from 20 grams gelatin in 1 liter water.

(b) like (a), but to 1 liter of surface solution is added 1.0 g. Ganex V-516.

(c) like (b), but 4 grams of Ganex V-516 are used Each of samples (a), (b) and (c) is sensitometrically exposed and developed in identical manner in the M4 X-Omat system. The results obtained are tabulated as follows:

As the result given in the above table make manifestly clear, the anti-foggant materials of the present invention make possible the realization of significant reductions in fogging while at the same time augmenting significantly both the speed and covering power of the light-sensitive composition. As Will further be noted, such dramatic improvement can be readily obtained despite the use of the alkylated polymer material in comparatively minimal concentrations. Thus, when included as a direct additive to an aqueous gelatin surface composition, concentrations on the order of but 0.1% by weight of the coating solution are found to impart to the subjacent sensitized emulsion layer superior covering power, resistance to fog and speed. An examination of the above summarized data reveals a further and significant advantage, i.e., the employment of the alkylated lactam material in increased concentration (not sample (b)) in no way deleteriously affects the melting point of the emulsion layer, i.e., the melting point of the emulsion remains unchanged. In addition, no scratch tendency is observed.

The following example compares the use of the antifoggant material of the present invention in conjunction with one of the more conventional types.

EXAMPLE IV A high speed, sulfur and gold sensitized silver halide emulsion containing 2% silver iodide and 98% silver bromide is prepared. Samples containing about 0.4 mole of silver halide are taken and experiments conducted as follows:

(a) coated as control and provided with a 4p. surface coating prepared from 20 grams gelatin in 1 liter water.

10 (b) like (a), but to 1 liter of the emulsion is added 0.3 gram of the polyoxyalkylene ether, material available commercially under the trade name designation Brij 35. (c) like (b), but to the emulsion sample is also added 2 g. Ganex V-5l6.

Each of samples (a), (b) and (c) is sensitometrically exposed and developed in identical manner in the M4 X-Omat system. The results obtained are tabulated as follows:

Again, the above results clearly demonstrate the synergistic results provided by the novel additives of the present invention. Of primary importance is the fact that the increase in speed obtained is attended by a minimal fogging level.

The present invention is not limited to any particular type of light-sensitive silver halide as it is useful with silver chloride, silver bromide, silver iodo-bromide, silver chloro-bromide, silver iodide, etc., emulsions and mixed emulsions of these types. However, particularly beneficial results are obtained with silver halide emulsions containing on the order of at least mole percent silver bromide with the remainder silver iodide.

The improvements provided by the present invention are not dependent upon the use of any particular type of silver halide developer. Accordingly, the latter may be of the hydroquinone type, i.e., those which contain hydroquinone, potassium metabisulfite and potassium bromide, or they may be of the metol-hydroquinone type, i.e, those which contain p-methylamine-phenol, sodium sulfite, sodium bisulfite, hydroquinone, sodium carbonate, and potassium bromide. Alternatively, the developer composition may be of the so-called borax type, i.e., those which contain p-methylaminophenol, sodium sulfite, hydroquinone, borax and potassium bromide.

The alkylated polymer materials of the present invention may be employed singly or in combination with other sensitizing addenda including for example, the noble metal sensitizers, e.g., gold salts, e.g., chlorauric acid and auric trichloride and, if desired, in association with sulfur sensitizers, e.g., sodium sulfite, thiosinamine, allyl-thiourea, sodium thiosulfate, allyl thiocarbonate, alkali metal thiocyanates and sodium sulfide; these sensitizers can be used in amounts up to 0.005% based on the weight of the silver halide. Moreover, the silver halide emulsions may contain one or more optical sensitizing agents, e.g., cyanine, carbocyanine, merocyanine, pseudocyanine and other cyanine dyes.

The light-sensitive emulsions employed may be those of the type intended for use in color photography, e.g., emulsions containing color-forming components which upon color development with a primary aromatic amine developer yield azomethine quinonimine or azine dyes. Suitable couplers are described in US. Patents 2,186,734, 2,445,254, 2,530,349, 2,671,021, 2,524,725, 2,354,552 and 2,547,037. Furthermore, the color coupler may be of the non-diffusing type which, when added to the silver halide emulsion dispersed in a mixture of high boiling and low boiling solvent form packet-type emulsions with encapsulated color formers. Suitable couplers of the latter type are described for example in US. Patents 2,179,239, 2,179,244, 2,298,443, 2,369,489 and 2,511,231.

The present invention has been disclosed with respect to certain preferred embodiments and they will become obvious to persons skilled in the art various modifications, equivalents or variations thereof which are intended to be included within the spirit and scope of the present invention.

What is claimed is:

1. A light-sensitive silver halide emulsion containing a stabilizer compound comprising an alphaolefin alkylated polymer of a heterocyclic N-vinyl monomer of the lactam series in which the alkyl radical of said polymer contains from 2 to 2000 carbon atoms.

2. A light-sensitive silver halide emulsion according to claim 1, wherein said heterocyclic N-vinyl monomer comprises N-vinyl pyrrolidone.

3. A light-sensitive silver halide emulsion according to claim 1, wherein said alpha-olefin alkylated polymer comprises a copolymer of a heterocyclic N-vinyl monomer and an a-olefin.

4. A light-sensitive silver halide emulsion according to claim 3, wherein said N-vinyl monomer comprises N- vinyl pyrrolidine.

-5. A light-sensitive silver halide emulsion according to claim 4, wherein said alkyl radical contains 16 carbon atoms.

6. A light-sensitive photographic material comprising a base and at least one light-sensitive silver halide emulsion said photographic material containing a stabilizer comprising an alpha-olefin alkyl-ated polymer of a heterocyclic N-vinyl monomer of the lactam series in which the alkyl radical of said polymer contains from 2 to 2000 -a carbon atoms.

7. A light-sensitive photographic material according to claim 6, wherein said stabilizer compound is present in an anti-abrasion layer overcoating said silver halide emulsion layer.

8. A light-sensitive photographic material according to claim 7, wherein said heterocyclic N-vinyl monomer comprises N-vinyl pyrrolidone.

9. A light-sensitive photographic material according to claim 7, wherein said alpha-olefin alkylated polymer comprises a copolymer of N-vinyl pyrrolidone and an aolefin.

10. A process for treating a light-sensitive silver halide emulsion material which comprises developing an exposed silver halide' emulsion in the presence of a stabilizer comprising an alpha-olefin alkylated polymer of a heterocyclic N -vinyl monomer of the lactam series in which the alkyl radical of said polymer contains from 2 to 200 0 carbon atoms.

References Cited UNITED STATES PATENTS 2,495,918 1/1950 Bolton 96-114 3,006,762 10/1961 Dersch 96-107 3,021,213 2/1962 DeISch et a1 96-107 XR 3,058,826 10/ 1962 Meerkamper et a1. 96-107 XR 3,060,028 10/1962 Dersch 96-107 XR 3,360,373 12/1967 Schaller et a1 96-114 NORMAN G. TORCHIN, Primary Examiner A. T. SURO PICO, Assistant Examiner US. Cl. X.R. 96-109, 114 

